Studies on F2 layer critical frequency in the southern hemisphere during solar cycle-23

Abstract

Annual and seasonal variability and anomalies of F2 layer critical frequency for 3 stations in southern hemisphere over solar cycle-23 (1996-2008) have been analyzed in this paper. Annual and seasonal variability have been studied by computing the yearly and seasonal coefficient of variability of F2 layer critical frequency. The annual analysis reveals that the variability of the equatorial station is comparatively lower at the solar active years of the selected solar cycle. For all stations, the variability is lesser at day time and peaks after midnight. During post sunrise hours the variability remains more or less same throughout the cycle in all stations. Variability is found to be higher mostly during equinoxes and the mean F2 layer critical frequency has been observed to peak around 1400LT, in all stations. Equatorial and mid-high latitude stations show semiannual anomaly throughout the cycle, while the mid latitude station exhibits no signatures of winter anomaly during the cycle.